When he and Larry Page created Google in 1998, they would
forever change how we use the Internet.

"When
Larry and I started the company, we had to get some hard drives
to, you know, store the entire Web," Brin
told Wired of Google's early days. "We ended up in a
back alley in San Jose, dealing with some shady guy. We spent
$10,000 or $20,000, all our life savings. We got these giant
stacks of hard drives that we had to fit in our cars and get
home."

But Brin doesn’t just like to challenge his mind. In his
spare time, he likes to push his body to the limits in any way he
can think of, from roller hockey and ultimate frisbee to
gymnastics, springboard diving, and even high-flying trapeze.
"I like to do a
variety of acrobatic things," he has said.

It turns out that athletics have long been a
priority for Brin.

Brin shows off his
gymnastics skills during a visit to Khan
Academy.Khan
Academy blog

Born in Moscow in 1973, he and his family emigrated from Soviet
Russia after
anti-Semitism made it difficult for his mathematician
father to get a job.

After receiving his bachelor's degree in math and computer
science at the University of Maryland, Sergey went on to pursue
his Ph.D. in computer science at Stanford, where he would meet
his future best friend and Google cofounder, Larry Page.

While at Stanford,
he tried out a variety of different sports, including in-line
skating, skiing, gymnastics, and trapeze. He spent so much
time on his various physical activities that his father once
asked him if he had chosen any advanced courses of study.

Even in the search engine's early days, Brin brought an
element of fun and activity to the Googleplex.

There have been plenty of stories of him arriving to
meetings in rollerblades, and his go-to outfit appears to be
workout clothes and Vibram FiveFingers barefoot shoes.
He sometimes
walks around on his hands, just for
fun.

In "I'm
Feeling Lucky," 59th Google employee Doug Edwards describes the
beginnings of Google, observing even the tiniest quirks of the
famous cofounders.

According to Edwards, at a 1999 company holiday event, Brin
tried to address party guests from the top of a giant red rubber
ball.

But, according to
Edwards' account, Brin "couldn’t
maintain his balance despite the trapeze classes he was taking at
a local circus."

That local circus was Circus Center, a training facility in
San Francisco's Inner Sunset neighborhood, where Brin would bring
Googlers for team bonding events in the company's early
days.

In 2009, he was
spotted in an advanced class at Circus Warehouse, a training
facility near the border of Queens and Brooklyn in New York City.
Greg Roberts, a San Francisco native who had flown out to New
York to participate in an immersive Cirque du Soleil-style
acrobatic yoga program at the facility, recognized Brin on the
second day of class.

"He was the only other person there who was interested in talking
about technology," Roberts told Business Insider. Roberts is an
avid acrobat and a serial entrepreneur who is currently working
on a 3D-printing company called dSky9. "Though we were both there
to kind of get away from tech and work on our bodies."

He was impressed with what he saw from Brin.

"People fly out from all over the world to take this class and
learn from some of the masters. I'd say [Brin] was in the top 20%
of the class," he said. "He was definitely giving his all."

A commercial for Google Glass gives a scary look at one
of Brin's favorite hobbies.YouTube,
Google

George Salah, who spent more than a decade as Google's
director of facilities before leaving for a startup in 2013,
initially joined the company after a roller hockey game with
Larry and Sergey.

"They were much better than I expected for a bunch of
engineers,"
he told Edwards.

Page and Brin showed up to
a 2008 conference in roller blades.Jacob Silberberg / REUTERS

Brin’s athleticism is especially obvious in comparison to his
sometimes awkward cofounder.

As opposed to Page, whom Edwards describes as having
"awkward moves and self-conscious grins," Brin is "more fluid,
athletic, acrobatic. Bouncy even. He laughed easily and seemed to
always have an eye out for a railing he could vault or a rafter
beam he could pull himself up on."

But there's an important motivation behind Brin's ongoing
enthusiasm for exercise.

In 2008, he learned that he had a mutation on his LRRK2
gene, a defect that would substantially increase his risk of
developing Parkinson's disease. Brin's mother, Eugenia, was
diagnosed with Parkinson's in 1999. Not everyone with
an LRRK2 mutation will get Parkinson's, but it does raise the
odds of developing the disease
from around 1% for the average American to between 35% and
70% for a carrier.

Brin discovered he carried a defective gene after
participating in a program run with 23AndMe, the genetic testing
company founded by his wife Anne Wojcicki, from whom he has since
separated.

But rather than resign himself to his fate, Brin has
decided to take steps to reduce his risk. He
estimates that with increased exercise and a healthy diet, he
could potentially cut his risk in half, to about
25%.

"I know early in my life
something I am substantially predisposed to. I now have the
opportunity to adjust my life to reduce those odds," he wrote in his
blog. "I feel fortunate to be in
this position. Until the fountain of youth is discovered, all of
us will have some conditions in our old age, only we don't know
what they will be. I have a better guess than almost anyone else
for what ills may be mine — and I have decades to prepare for
it."

As a
multi-billionaire, Brin also has the means to support research
into finding a cure for the disease he might develop some day. As
of February 2014, he and Wojcicki had donated
nearly $95 million to the Michael J. Fox Foundation for
Parkinson's Research, including a $32 million gift in
2013.

"If I felt it
was guaranteed to cure Parkinson’s disease, a check for a
billion dollars would be the easiest one I have written,"
Brin told Bloomberg. "Pretty much everybody in the
world has or will have some serious condition. How much is it
worth to you to have that condition be potentially
curable?"